A controversial experiment to artificially cool the Earth has been aborted – what we know about the reasons

After years of preparation, Harvard researchers have canceled plans to test a controversial theory about cooling the planet by sending sunlight-reflecting particles into the atmosphere. Now members of an independent advisory committee that looks into ethical and safety issues are reporting what they learned from the ill-fated project.

A political analysis published in the journal Science on Friday stressed the importance of talking to local people before launching an experiment, especially one with potentially planet-changing consequences. The paper reiterates recent calls to put measures in place to protect against unintended side effects.

Until recently, the idea of ​​beaming sunlight back into space to combat global warming – a process known as solar geoengineering – seemed firmly rooted in science fiction. But as the climate crisis worsens, the idea has begun to move out of the fringes of academic research and into more serious debate.

Some researchers and their Silicon Valley supporters want to put the theory to the test. And time is running out to establish rules for the responsible conduct of such experiments that could help determine whether solar geoengineering does more harm than good.

“One of the key messages is that public engagement is necessary, even if you don’t believe that the effects of the experiment will be real, concrete and felt in real time. This issue has such a long-lasting resonance and such a deep meaning for so many people,” says Sikina Jinnah, lead author of the Science Policy analyst and professor of environmental studies at the University of California, Santa Cruz.

Harvard researchers started the project, called SCoPEx – short for Stratospheric Controlled Perturbation Experiment – back in 2017. To better understand the potential risks and benefits of solar geoengineering, they planned to conduct the first outdoor experiment using reflective particles. This would involve releasing some of these aerosols into the stratosphere by balloon and then flying the balloon back through the cloud to take measurements. The goal was to observe how the particles interact with each other and with other elements of this environment – leading to data that could be used to create more accurate computer models.

However, that never happened. A technical test flight without particle release was scheduled to take place in Sweden in 2021, but was cancelled due to strong opposition from local indigenous leaders. A major point of contention was that the researchers had not initially contacted the Saami Council, which represents the organizations of the indigenous Saami peoples in the region. SCoPEx Advisory Committee members disagreed on whether to consult the Saami, since the test flight would not release anything into the atmosphere according to the policy analysis. The majority ultimately decided that the test flight could go ahead if there were no significant environmental concerns.

The Saami Council caught wind of the plans anyway and wrote a strongly worded letter to the advisory committee urging the researchers to cancel the flight. They said it was “remarkable” that the test flight was being carried out without consultation with the Saami people or other local stakeholders, given the controversy raging around solar geoengineering. Local environmentalists, including Swedish chapters of Greenpeace and Friends of the Earth, also signed the letter.

Solar geoengineering is still seen by many activists as a “false solution” to climate change. By injecting particles into the atmosphere, it is designed to mimic the way volcanic eruptions can temporarily cool the planet by releasing sulfur dioxide. But sulfur dioxide could also cause acid rain, increase the ozone hole in Antarctica, or have other unforeseen consequences. There are also fears that solar geoengineering could undermine efforts to transition to clean energy or cause dangerous increases in global temperatures if it is ever implemented and then abruptly stopped.

“We note that (solar geoengineering using reflective particles) is a technology that carries the risk of catastrophic consequences… There are therefore no acceptable reasons for allowing the SCoPEx project to be carried out in Sweden or elsewhere,” the Saami Council letter said.

After receiving that letter, the advisory committee ultimately recommended canceling the test flight in Sweden. By 2023, Harvard informed the advisory committee that it had “suspended” the project, and then canceled it altogether in March of this year. The project “struggled both with intense media attention and with how to respond to the Scientific Advisory Committee’s calls to fully and formally engage the public.” Nature reported at the time, citing one of its project managers.

“I am grateful for the insights of the SCoPEx Advisory Committee. Their careful analysis is valuable to the scientific community as it addresses important governance issues,” says Frank Keutsch, SCoPEx’s lead researcher The edge in an email. He did not elaborate on why the project was terminated.

According to the newly published policy analysis, it will take more than an ad hoc committee to effectively oversee geoengineering research in the future. “The time is ripe for governments to discuss coordinating research governance,” it says.

These discussions have already started at the European Commission and the United Nations Environment Assembly, but have not yet led to concrete new measures. Since the United Nations Biodiversity Conference in 2010, a moratorium on large-scale geoengineering has been in place, but it excludes small-scale scientific research.

And recently, small, shady initiatives have become a bigger problem. Last year, the founders of a geoengineering startup grilled fungicides in a California parking lot to create sulfur dioxide gas, which they then tried to launch into the atmosphere using weather balloons. A similar balloon launch in Mexico prompted the government there to ban experiments with solar geoengineering. The policy analysis calls the startup’s efforts “irresponsible” and “not connected to a legitimate scientific goal.”

Since then, there have been calls to either set rules to regulate future experiments or to stop solar geoengineering altogether. But without more comprehensive policy action, keeping up with new geoengineering efforts is increasingly becoming a global game of whack-a-mole.

These policies could also ensure that surrounding communities have a say in projects that might affect them. And as we learned at SCoPEx, even more careful efforts can skip this step to their own detriment.